This invention relates generally to an audio apparatus and, more particularly, is directed to an audio apparatus which provides automatic tone balance of a reproduced acoustic signal.
Electronic audio apparatus for producing an acoustic signal from a record medium or other audio source is well known in the art. Typically, in such apparatus, electronic audio frequency signals are reproduced from an audio source, such as a phonograph, tape recording/reproducing apparatus, FM/AM radio tuner, or the like, and supplied through an amplifying circuit to a loudspeaker for acoustic reproduction. That is, the output of the amplifying circuit is used to drive the loudspeaker to produce an acoustic signal in response thereto.
As is well known, a loudspeaker typically includes a diaphragm which has vibratory motion imparted thereof in response to the signal received from the amplifier, which vibratory motion produces a sound pressure wave which is heard by the listener as the reproduced sound or acoustic signal. However, because of varying factors in loudspeaker design, such as shape, size and construction, the reproduced acoustic signal does not always accurately reflect the audio signal it is designed to reproduce. Thus, variations in tonal quality may be readily apparent in the reproduced acoustic signal. Although manual tone controls are typically provided for adjusting the tonal quality of the signal applied to the loudspeaker, a loudspeaker may affect the tonal quality of an acoustic signal differently for audio signals reproduced from different sources. Therefore, the tone controls may have to be adjusted for different audio sources so that no fixed tone control setting can be made. Such variation in tonal quality is even more evident between loudspeakers of different design.
In like manner, variations in room geometry and dimensiors greatly affect the sound balance and perceived tonality of the reproduced acoustic signal, even when the same loudspeaker is used. Such variations in tonal quality are even more evident when loudspeakers having different designs are used in rooms having different geometries and dimensions. Thus, individual listeners frequently find it difficult in deciding on the best combination of loudspeaker and room design to produce an accurately reproduced acoustic signal.